This is how I generate worlds. I have carefully pre-made with Perfect World template, with every parameter carefully adjusted, and most of geographic features painted by hand. You don't want to know how much time I spent on fine-tuning it. So, the only thing left for RNG's mercy is biomes and temperature poles. Now, I want the hot pole to be on the north, because this is where most of mountains is, so I could trade elephant leather with dwarven caravans.
So, if the poles are other way around, I abort worldgen. This is easy, because you can see the dislocation of the poles immediately after beginning of world gen. So it takes only maybe half a minute.
Then it gets worse.
I have two oceans. Big and very big. I want the very big one to be evil biome. Not because I want to build my fortress on its shores, no. But because I like the picture of female dwarves, putting their children to bed, and telling them stories about The Great Ocean Of Inevitable Doom, from which the terrifying zombie whales comes to walk this land.
And no, the smaller ocean wouldn't suffice. Because then it will looks like it only tiny evil part of blue and beautiful Ocean Of Hope. And we don't want that, do we?
Anyway, back to the topic. During worldgen, evil and good biomes placed after the caves. That is, after roughly to minutes of worldgen. Naturally, I can't just sit and wait and do nothing all this time. So I switch to something else. Often to this forums. And by the time I remember to check, 500 years of worldgen passed already. And if bigger ocean is not evil, I abort worldgen. So, this all takes roughly 10 minutes. Multiply by the number of repeats needed to get just that one ocean to be evil.
So, 2 hours later, finally, we get perfect world.
Well, it wouldn't count as OCD if it would be so easy, would it?
We finally get to see the names of dwarven civilizations. Wait, what is it? There is no names dwarven enough? No Axes of Rage and Diamonds of Perfection? All you see is Lovely Boat? There is only one possible solution. Delete the world and regen it from scratch.
This can continue for days. Record is 10 days so far.
After the world finally generated, the rest is easy. Just pick good spot (and if you can't find good enough after more the 2 hours of search, regen the world) and proceed to dig\build fortress. And may the gods forgive you if you dug entrance to the room 7 tiles from the right side instead of 8.
TL;DR: I generate worlds. Often, long and painfully.